Samuel Pierpont Langley was the first Director of the Allegheny Observatory and held that position from 1867 to 1887. His primary interest was the sun and he began his studies of the sun immediately after assuming the post of Director. Langley prepared drawings of sun spots and associated phenomena and astronomers, today, are still familiar with Langley's classic drawing of the great sunspot of 1873.

In 1869 Langley devised and made operational the electric system of transmitting telegraphic time to several of the Pennsylvania Railroad lines which were associated with the observatory. In the area of magnetic disturbances, Langley was the first to associate such disturbances on the earth with solar outbreaks of an extremely active character.

Concerning studies in the realm of solar physics, Professor Langley was impressed with the idea that much radiant energy from the sun could not be recognized with instruments then in use, and after much experimentation, he invented the bolometer. With this instrument he succeeded in measuring the amount of heat radiation on the earth from the sun (the solar constant).

Professor Langley studied many minor though important questions concerning radiant energy. His investigations of the moon's temperature added greatly to our knowledge of the moon. Langley used his spectrobolometer to measure the highest temperature of the moon which was found to be approximately zero degrees centigrade and the lowest temperature of the moon which was found to be equivalent to the temperature of space.

Langley also collected data on the part of the solar system beyond the infra-red zone. With the aid of Professors Keeler, Very, and Page measurements were made by Langley utilizing the spectrobolometer and the galvanometer which he invented before photographic methods were develop.

Langley, of course, has received much recognition for his contributions to aeronautics. However, his original intention was not to construct a flying-machine, but instead to "determine the laws governing flight." At the Allegheny Observatory, Langley built a whirling arm on which "he tested airfoils, fusiforms and other aerodynamic objects, measuring their angels and pressures as they moved through the air at varying speeds." Studies of actual birds and "mechanical birds" ("winged contrivance" made of tin, cork, and rubber) were conducted and findings published in a paper entitled "Experiments in Aerodynamics."

Professor Langley left his post at the Allegheny Observatory in 1887 (leaving F.W. Very, his assistant, in charge) to become Assistant Secretary of the Smithsonian Institution; later, following the death of Professor Baird, he was elected Secretary of the Institution in 1891. Langley continued his research in aerodynamics and from a catapult, on May 6, 1896, launched an unmanned, steam-powered flying machine over the Potomac. It flew more than a half mile and was subsequently recovered. The first manned flight of his gasoline-powered "aerodome" failed in 1903 because of a launching device defect. Glenn Curtiss successfully piloted Langley's restored plane eight years after his death.

Note: Calendar entries covering the period 1884-1889 (Letterpress books no.'s I, II, and III) consist of abstracts of letters selected from four areas of research: 1) magnetic disturbances, 2) solar radiation, 3) mapping of infra-red spectrum, and 4) aerodynamics. There are also selected abstracts relating to both the electric time signal service and miscellaneous correspondence.

Please note that references to pagination indicate number of pages letters occupy in letterpress books and not necessarily number of pages of actual letters.

Box 30

Volume

1

Samuel Langley, 1862-1872

Volume

2

Samuel Langley, 1884-1887

This calendar, comprised of Volumes 2-3, was prepared by David Lieberman, a student in the Graduate School of Library and Information Sciences, University of Pittsburgh, as an independent study project during September - December, 1973.

2. Brashear, J.A. Allegheny, PA. Has examined Brashear's lens specimens and has enclosed several items including a bolometer carriage in order that Brashear might measure from it to prepare his own, 2p., March 7, 1884

3. Grunow, William. West Point, NY. Langley waiting with great interest the result of experiment with a 1/20 mm. single strip bolometer. [Page 2 of letter not legible, Ed.], 2p., March 7, 1884

4. Grunow, William. West Point, NY. A firm in Paris wishes to secure bolometers for the purpose, Langley supposes, of constructing others, 1p., March 8, 1884

5. Thaw, William. Allegheny, PA. A discussion of the conditions which cause a rise in the surface temperature of the Earth, 1p., March 14, 1884

6. Grunow, William. Encloses a draft for $100 for payment of construction of four bolometers, 2p., March 18, 1884

16. Snyder, W.B. Philadelphia, PA. Forwarding bolometer to the International Electrical Exhibition at the Franklin Institute, 1p., May 19, 1884

17. Brashear, J.A. Allegheny, PA. Langley proposes to use, in place of a concave mirror of silver copper, a flat mirror silvered on the front face in order to read the reflected scale of his galvanometer, 2p., May 21, 1884

25. Brashear, J.A. Allegheny, PA. Langley requests preparation of a glass cover mirror to be used in a new spectroscope, 1p., September 27, 1884

26. Thomson, William. Glasgow, Scotland. Allegheny Observatory has obtained conclusive evidence as to the character of the ultra-red bands. Suspects that they are probably telluric, 2p., October 6, 1884

42. Tatlock, John. Beloit, Wisconsin. States that the Allegheny Observatory was the first to establish an electric time service to railways, 2p., July 3, 1885

43. Bramwell, Frederick. London, England. Acknowledgement of receipt of communication of May 14, 1885 extending thanks to members of Royal Institution for expression of their satisfaction with discourse delivered in April 1885, 1p., July 7, 1885

44. Blanford, Henry F. Langley inquiring about the temperature of surfaces of "rock or soil, uncovered by snow, at very great altitudes", 2p., July 14, 1885

45. Whymper, Edward. London, England. Has forwarded a copy of observations on Mt. Whitney in the Sierra Nevadas which discusses primarily theoretical temperatures of airless planets, 2p., July 14, 1885

50. Brashear, J.A. Allegheny, PA. Langley requests that Brashear observe "siderostat to see whether a needed adjustment can be introduced to make the telescope [Langley;s] parallel to the declination (and free from present shake)" Sketch enclosed, 2p., October 28, 1885

51. Goldback, C. Kehl, Germany. States that observatory is using rock-salt for researches on radiant heat, 1p., November 7, 1885

52. Grunow, William. West Point, NY. Requests construction of a bolometer to consist of 3 central strips each 1 mm. wide and 10 mm. in length to be made of platinum which was "heavier than usual", 1p., November 7, 1885

53. Austin, W.W. Johnstown, PA. Response to letter of inquiry requesting longitude and local time of Johnstown, 1p., November 24, 1885

55. Brashear, J.A. Allegheny, PA. Discusses conversation with W. Thaw. Request for two 18 mm. discs. Also Langley requests Brashear's presence so that he might present him with a sketch and definite order for work to be done on galvanometer, 2p., November 30, 1885

56. Barber, D. Professor Langley wishes to purchase an economical storage battery which will be efficient in maintaining a steady dynamo current, 1p., December 1, 1885

57. Brashear, J.A. Allegheny, PA. Langley requests that the following work be executed for Allegheny Observatory: 1) construction of small mirrors for galvanometer; 2) adjustment of galvanometer back and head screw; 3) construction of scale lamp; 4) construction of siderostat and siderostat mirror; 5) construction of other mirrors. Memoranda supplying specifications and sketches enclosed, 7p., December 4, 1885

58. Brashear, J.A. Allegheny, PA. Request for a larger lens [usage not specified, Ed.] and a modification of previous order for siderostat mirror. Sketch enclosed, 1p., December 5, 1885

70. Frost, A.G. Youngstown, Ohio. "Approximate relative positions of the Sun, the Earth and Venus in January 13, 1886 viewed from the North Side of the Plane of the Ecliptic" Sketch enclosed, 1p., ca. January

82. Grunow, William. West Point, NY. Carbon bolometer "a mechanical success" but does not perform as well as expected, 3p., March 29, 1886

83. Ball, John. London, England. Langley discusses temperature variations of the soil of the full moon, 2p., April 19, 1886

84. Marson, G. Paris, France. Submitting by mail to Annales de Chimie et de Physique in a few days complete illustrations for an article on "Invisible Spectrum and their wavelengths", 1p., April 19, 1886

85. Thomson, William. Glasgow, Scotland. Research just completed on the relation of the index of refraction to wavelength by utilizing a mirror galvanometer, 1p., April 19, 1886

87. Grunow, William. West Point, NY. New bloomer case received and is "very satisfactory", 1p., May 17, 1886

88. Thomson, William. Glasgow, Scotland. Soon to announce research completed in the area of the heat spectrum, 1p., May 18, 1886

89. Grunow, William. West Point, NY. Langley returning bolometer No. 4 because its "working badly having very unequal resistance" Requests its immediate return and wishes to know with what thickness of platinum it is filled, 2p., May 19, 1886

91. Darwin, G.H. Cambridge, England. Langley states that he is conducting research on wavelengths in the infrared spectrum and most probably will not be able to attend an international conference in England, 2p., May 29, 1886

96. Marson, G. Paris, France. Submitting by mail to the editor of Annales de Chimie et de Physique the completed manuscript of the research referred to in the Comptes Rendus of January 18, 1886, 2p., June 9, 1886

98. Grunow, William. West Point, NY. Refilled bolometer No. 14 which arrived in "good order" Several bolometers in need of repair are forwarded along with a new alloy which is said "to possess superior qualities for a bolometer." Lastly, Grunow is cited in European journals as the manufacturer of the Langley bolometer, 2p., June 11, 1886

99. Kedzee, J.H. Chicago, Illinois. A critique of a book written by Kedzee on solar radiation, 1p., June 12, 1886

110. Hall and Sons. Buffalo, NY. Instructions for modifying construction of a crucible to be used in determining the radiation of "an entirely fixed temperature which will be given out by a piece of platinum placed at the closed end of a tub", 2p., November 16, 1886

112. Grunow, William. West Point, NY. Bolometer No. 13 "turns out to be all right". "Langley makes some slight modifications for the future construction of the bolometer thread," and inquires as to whether European orders for bolometers have increased, November 18, 1886

145. Johnston and Co. Pittsburgh, PA. Rubber band received buy lacking in both strength and weight. [Related to flight experimentation, Ed.], 1p., March 9, 1887

146. Rayleigh. Presently conducting experiments on the resistance of air of bodies in motion. Tequest for recommendations concerning any line of investigation likely to be of special interest, 1p., March 9, 1887

147. Thurston. Langley requests information on: first, the names of modern authorities "on air in motion at various inclinations to it"; second, the title of a modern work on wind mills; third, information of the Cunard streamers. Fourth, the name of a "really intelligent and trustworthy model-maker", 2p., March 9, 1887

148. U.S. Army, Chief Signal officer. Washington, DC. Request for information pertaining to resistance of plane surfaces to air in motion, 1p., March 9, 1887

149. Grunow, William. West Point, NY. Langley wishes to order a new bolometer to be numbered 20, L., 1p., March 19, 1887

150. White, James. Glasgow, Scotland. Modifications to be made in construction of a galvanometer. Sketch enclosed, L.,1p., March 19, 1887

151. Phillips and Co. Request for elastic rubber [probably to be used in aerodynamic experimentation, El.], 1p., March 26, 1887

152. Phillips and Co. Pittsburgh, PA. Submitting order for elastic rubber to be used in aerodynamic experimentation, 1p., March 28, 1887

176. Queen and Co. Philadelphia, PA. Second request for ordering information pertaining to tachometer and tachograph, 1p., June 18, 1887

177. Hazen, Allen. Washington, DC. Erecting a Whirling Table of "exceptional size" to carry out experiments in anemometry and the resistance of air to bodies in motion including railroad trains. Expects to make experiments in fall with a locomotive and platform cars, 2p., June 25, 1887

182. Abbe, Cleveland. Washington, DC. Request for a chronograph cylinder to be used for aerodynamic experimentation, 2p., July 5, 1887

183. Rotch, A. Lawrence. Request for data on the varying velocity of the wind during short intervals of time, e.g., every quarter of minute or less. Further that Rotch request attach a chronograph to an anemometer which would record electronically the varying velocities on a uniformly revolving board, 2p., July 5, 1887

184. Rowe, Charles O. Titusville, PA. Request for a pole to be set up close to the Observatory with wires leading to the top of chromograph [Probably be used in measurement of wind velocity, Ed.], 1p., July 5, 1887

188. Rotch, A. Lawrence. Acknowledgement of receipt of chronographic record. Requests that record should in the future be obtained on a time scale, ten times as long, "so that the changes from minute to minute can be recognized during an hour or so", 1p., July 13, 1887

189. Rowe, Charles O. Titusville, PA. Acknowledgement of receipt of pole used in connection with chromograph, 1p., July 14, 1887

190. Description of "self recording apparatus to be placed at end of arm of great Whirling Table", 8p., July 15, 1887

8. White, James. Glasgow, Scotland. Generally pleased with finish and solardarity of galvanometer. However, hinges to enable magnets to be unclasped from glass rod were disregarded, 1p., February 2, 1888

9. Brashear, J.A. Pittsburgh, PA. Preparation of a box of seasoned pine to hold the new "White" galvanometer, L., 3p., February 3, 1888

10. Grunow, William. West Point, NY. Final modifications of dynometer - chronograph made by Brashear in Pittsburgh, T.L.S., 2p., February 16, 1888

18. Witchell. "Taking measures of the intensity of different colored lights taking for instance red, yellow, blue, or any number of other spectral colors from the same sources and same prism, and trying the comparative intensities of each by noting the relative illuminating powers by suitable tests for the normal eye", 1p., March 30, 1888

22. Grunow, William. West Point, NY. Concerning construction of a spectrobolometer which must be completed within ten months, 2p., May 11, 1888

23. Hale. No French engines for utilizing solar heat more recent than those of Mouchot, exhibited in 1878. French commission report engine not feasible to operate. J. Ericson's engine not economically feasible to operate, 1p., May 11, 1888

25. Reuben, Levi. New York, NY. Acknowledgement of receipt of the book, Travels in the Air. Langley states also with regard to inequalities in the distribution of clouds and rain that he cannot render a judgment on such a meteorological question, 1p., May 15, 1888

26. Thomson, W. Philadelphia, PA. Request for the title of the best treatise on color vision, L., 1p., May 24, 1888

27. Thaw, William. Pittsburgh, PA. Statement of cash receipts and expenditures of the Allegheny Observatory also includes annual report 1887/88 on the "scientific labors of the Observatory" [one page not legible, Ed.], T.L.S., 6 p., ca. May

34. American Journal of Science. New Haven, CT. Enclosed copy of article entitled "Energy and Vision" for November publication, 1p., September 28, 1888

35. American Journal of Science. New Haven, CT. Concerning the return of the proof copy of an article entitled "Energy and Vision", 1p., October 23, 1888

36. London, Edinburgh, and Dublin Philosophical Magazine. Forwarding proof of an article on "Energy and Vision", which was expected to appear in the American Journal of Science for November, 1888, 1p., October 23, 1888

37. Gibbs, Wilcott. Newport, RI. Langley prepared to make a personal examination of disposition of Bache fund for purposes specified on researches in solar physics; description of research in progress, 2p., November 5, 1888

40. American Journal of Science. New Haven, CT. Request for 500 copies in paper covers of History of a Doctrine, 1p., December 3, 1888

41. Ballot, Buys. Ultrecht, Holland. Will post in a few days an abstract of the paper, "On the Solar and Lunar Spectrum," published in the December 1888 issue of the Journal of Science, 2p., December 3, 1888

42. Turner, S.E. Pittsburgh, PA. Wishes to have the "shaft of the turn table made frictionless", 2p., December 3, 1888

Volume

4

Samuel Langley, Frank Very, and James Keeler, 1889-1891

1. [Memorandum] Authorization for removal of pieces of apparatus, which were the personal property of Mr. W. Thaw, to the personal charge of Langley. Signed by W. Thaw, A.D.S., 2p., June 19, 1889

2. Annual Report [1888/89] of the Director of the Allegheny Observatory, A.D.S., 4p., ca. June

Box 31

Volume

1

James Keeler, 1887-1894

Volume

2

Frank Very and James Keeler, 1892-1895

Volume

3

James Keeler, John Brashear, F.L.O. Wadsworth, and Henry Harrer, 1895-1901